,,Hard questions do filter out bad engineers, but they also filter out good engineers (that is, they have a high false-negative rate). Easy questions, in contrast, produce fewer false-negatives but more false-positives''

The philosophy at Google is that it's better to filter out 3 good engineers than to let in a bad one. The consequence of this is that it's really hard to get kicked out of Google.

The other part (whether it's more important to work on long easier questions to see how the candidate works on a large code base) is orthogonal reasoning, and that part may be true, depending on what type of engineers somebody is looking for.